/Engine/Source/Editor/BlueprintGraph/Classes/K2Node.h
Renames a user defined pin and broadcasts the result to any OnUserDefinedPinRenamed listeners on success (if bTest is false)
ERenamePinResult RenameUserDefinedPin ( const [FName](API\Runtime\Core\UObject\FName) OldName, const [FName](API\Runtime\Core\UObject\FName) NewName, bool bTest )